MIAMI (CBS4) –As investigators continue to piece together the mystery surrounding a pesticide truck parked along the side of I-95 in West Palm Beach that sent a father and son to the hospital, a senior law enforcement source has told CBS4 News the body found in a bag inside the back of the truck is believed to be the driver’s 10-year-old adopted daughter.

The girl was the twin sister of Victor Vocter, the 10-year-old boy rescued from the truck, according to the source. Now, the children’s father is chaged with aggravated child abuse, accused of injuring the surviving child inside the truck. “We can’t really specify,” explained police spokesman Chase Scott. “But an instance that occurred here on the side of I-95 with his 10 year old son, that’s where the aggravated child abuse charge stems from.”

We do know the child suffered severe burns. “He did suffer some burns from the chemicals that were on his clothes and his body as well as some internal issues,” said Scott, “some severe internal reaction to breathing in the fumes of the chemicals.”

The body remained on the scene until 8:30 in the evening. The strength of the chemicals made it hard to move the body. In fact, just to get it into the medical examiner’s vehicle was difficult. “I believe they tried to do a partial decontamination,” Scott explained. “Then the bag was placed into another bag, which was placed into another bag, then on the gurney and then placed into the vehicle for transport.”

One day after the disturbing discovery, it is still a very active scene near the Palm Beach Lakes Boulevard exit on I-95, except now several large tents cover the small red pickup truck where the body was found.

Chase Scott said while he could not say the body on the truck was not the twin girl, someone saying so now “would have to have x-ray vision”, because the body is still wrapped in plastic, surrounded by hazardous material, and has yet to be unwrapped as experts work to decontaminate the scene.

The discovery was made Monday when a Road Ranger stopped to assist the driver of what he thought was a broken down truck which had the words “C. J.’s Pest Control Miami” on its side.

When the ranger approached the truck he found the driver, Jorge Barahona, 53, of Southwest Miami-Dade, and his 10-year-old adopted son, Victor Vocter, conscious but having breathing difficulties.

Barahona was taken to Columbia Medical Center with a unspecified medical condition caused by the chemicals and the son was taken to St. Mary’s Medical Center. Both are said to be in fair but stable condition.

It was when firefighters on the scene also started feeling sick that a hazardous materials crew was called in to take over the investigation. In the back of the truck they found a leak in a container which contained acid. It’s believed that fumes from this chemical were what sickened Barahona, the boy and four firefighters. According to police, the chemical is not the type typically used in pest control but it is used to clean metal.

It was while the Haz-Mat team were looking through the truck that they spotted something unusual.

“The Department of Environmental Protection went into the rear of the vehicle, moving aside some chemicals,” said Chase Scott, spokesperson for the West Palm Beach Police department, speaking to reporters late Monday night. “(They) located a body in a bag in the rear of the vehicle.”

With the discovery of the acid and the body, Miami-Dade Police and Fire Rescue Haz-Mat were sent to Barahona’s home in the 11000 block of Southwest 47 Terrace in Southwest Miami-Dade to search for more potentially dangerous chemicals and possible clues as to why Barahona had a body in his truck.

Neighbors said Barahona regularly parked his truck in front of his home and kept a steel container full of pesticides on his property. Jim Sheppard said he never noticed a problem.

“He was always very cautious when he did his stuff,” said Sheppard. “He sprayed my house, and when he came in and sprayed my house he’d always put on a big respirator and ask me to step out. He’s always really cautious and careful about the chemicals.”

Late Monday, the FBI joined the investigation, though no reason was given for the federal interest.

According to state records, Barahona operated his business out of his home. Last week, he filed with the Florida Secretary of State to use the name C.J.’s Pest Control for his business. The Florida Secretary of State’s office said Barahona had operated a business as C.J.’s Pest Exterminator, Inc., since March of 1998. That corporation was dissolved by the state last September, when he failed to file the proper state documents.

Barahona’s wife, Carmen, was holed up inside her parents Southwest Miami-Dade home with two of the couple’s four children, according to CBS4′s Gary Nelson. But the two children were removed from the home by child welfare officials.

The couple has four adopted children, ages 7 through 11, according to the Department of Children and Families. Those children are under DCF protective supervision at the grandparents home, according to DCF’s Mark Riordan.